Could someone explain the reasoning for this?
6) Which of the following is a false statement about ALL reactions in equilibrium?
a) Increasing temperature shifts the reaction toward the products in an endothermic
reaction
b) Temperature effects on the equilibrium do not depend on ΔS
c) Increasing the amount of a solid salt (already present) will increase the ion
concentrations
d) All of the above
e) None of the above
I know the answer is C--but am not sure why. I know A is the opposite of what is stated, and B I am a little wishy washy on understanding it.
Since you no c is correct, we can do away with d and e.
A is a true statement, contrary to what you say in your post about it being opposite.
A + B + heat ==> C + D.
Adding heat makes the reaction shift in order to use up the heat added; it can do that by shifting to the right using up heat in the process and making more of the products.
B. It may depend on delta S for some but not ALL equilibrium reactions.
C. A solid salt, already present, means you have a saturated solution. Therefore, the concn of the ions is as large as they will get. Although the solution process is dynamic, meaning that some ions are coming out of solution to form the solid while the solid is dissolving to form more ions in solution, the net total of the + ions remains the same and the net total of the - ions remains the same. Since it is already a saturated solution, the ion concentrations can't become larger.
To understand why option C is the false statement, let's break down each option and analyze them:
a) Increasing temperature shifts the reaction toward the products in an endothermic reaction
In an endothermic reaction, heat is absorbed from the surroundings, so increasing the temperature will favor the reaction in the forward direction to consume the heat. Therefore, this statement is true.
b) Temperature effects on the equilibrium do not depend on ΔS
Temperature effects on equilibrium depend on both ΔH (enthalpy change) and ΔS (entropy change). The ΔH determines the heat absorbed or released during the reaction, while ΔS represents the change in randomness or disorder. Together, they determine the equilibrium position. Therefore, this statement is false.
c) Increasing the amount of a solid salt (already present) will increase the ion concentrations
This statement is false. Adding a solid salt that is already present will not affect the ion concentrations. In equilibrium, the concentrations remain constant, and adding more of an already-present solid does not change the equilibrium state.
d) All of the above
Since option C is false, option d cannot be true because it includes C. Therefore, option d is not the correct answer.
e) None of the above
Since option C is found to be false, option e (none of the above) cannot be true either.
Therefore, the correct answer is C - Increasing the amount of a solid salt (already present) will increase the ion concentrations.